Often it is desirable to provide a visual indication of the level of liquid in a container of opaque material such as wood, metal or the like. To this end, a common practice has been to utilize a vertically extending tube or sight gauge preferably of transparent material such as glass provided with suitable gradations. The lower end of the tube is connected in communication with the liquid in the container so that the liquid level in the tube and container will remain the same when the pressure which may be atmospheric pressure, on the surface of the liquid in the container and tube is the same. In such an arrangement, as liquid is removed from the container, the level of liquid in the tube follows the liquid level in the container thereby providing as a continuous indication of the quantity of liquid in the container.
Since such a sight gauge is of simple and inexpensive construction, it has been proposed to ulilize such a gauge with a liquid container wherein the liquid is maintained under pressure as in a beer keg or the like. As is well known, the supply of liquid or beer in a container such as a beer keg is maintained under a constant pressure by means of a pressurized gas for periodic dispensing of the liquid from the container and conveyance of the liquid to a point of use at a remote location. However, such an adaptation has presented certain problems in in that the liquid in the sight gauge which is connected in liquid communication with the interior of the container through the dispensing conduit, must be subjected to the same pressure as that of the liquid in the container for the liquid levels in the gauge and container to remain the same. Therefore, gas by means of which pressure is maintained in the container is introduced into the upper end of the sight gauge so that the same pressure applied to the surface of the liquid in the container is applied to the surface of the liquid in the sight gauge with the result that the liquid levels remain the same and the sight gauge provides a visual indication of the quantity of liquid in the container. However, in such an arrangement, as a result of the liquid communication between the container and the sight gauge, the dispensing of a quantity of liquid from the container is accompanied by the ejection of the liquid in the gauge tube under the force of the pressurized gas introduced into the top of the gauge tube and the attendant presence of gas in the dispensing conduit.
It has therefore been proposed to provide an on-off, manually operated valve in the conduit which connects the lower end of the gauge tube with the container dispensing conduit which valve is normally maintained in the closed condition during periodic dispensing of liquid from the container. When an indication of the liquid level in the container is to be obtained, the valve is opened to permit the liquid to flow from the container into the tube with equal pressure being maintained on the liquid in the container and tube thereby permitting the liquid level in the tube to assume the level of the liquid in the container and providing a visual level indication.
It can be readily understood however, that as long as the valve remains in the closed condition, the liquid level in the gauge tube will remain unchanged even though the level of liquid in the container drops due to dispensing of the liquid therefrom. It is therefore necessary to open the valve to permit the liquid level in the sight gauge to drop to the level of the liquid in the container for a visual level indication and then reclose the valve for further dispensing. An example of such a level indicator and more particularly a beer keg is shown in U.S. Pat. No. 3,311,267 entitled Measuring Attachment For Beer Keg of the Like issued March 28, 1967, to R. L. Lee et al. The disadvantages of such a prior art structure can be easily seen in that the true level of liquid in the container can be observed on the sight gauge only after the valve has been opened and reclosed which is not only time consuming and inconvenient but does not provide a continuous indication of the level of the liquid in the container.
Accordingly, the primary object of this invention is to provide a new and novel liquid level indicator for a container such as a beer keg of the like.
Another object of this invention is to provide a new and novel liquid level indicator for a container of the type in which liquid to be dispensed is maintained under pressure.
A further object of this invention is to provide a new and novel liquid level indicator for a pressurized container such as a beer keg which accurately indicates the liquid level in the container at all times and which is unaffected by the dispensing of liquid under pressure from the container.
This invention further contemplates a new and novel liquid level indicator for a beer keg in which beer is maintained in a pressurized condition for periodic dispensing which is simple and inexpensive in construction, which may be easily attached to a keg of the type commonly provided by breweries and the like for marketing beer, which utilizes a minimum of readily available low cost component parts and which continuously provides an indication of the liquid level in the beer keg from a full condition to an empty condition.